Riverside, CA 92508 Frost Dates
Riverside, CA: when does the frost end?
Typically, the last spring freeze lands around 01/09, roughly 134 days out. Fall's first freeze usually shows up around 12/25, roughly 353 days after the last spring frost.
Riverside sits in USDA Zone 9b (25 to 30°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
Stretching the season past the first frost
With roughly 17 weeks until Riverside's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
The actual range around Riverside's last frost
01/09 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/25 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 12/16 and only about 1 year in 10 sees frost after that.
Riverside against the rest of the dataset
About 353 days separate Riverside's last and first frost, putting it 2,203 of 40,283 ZIP codes nationally. Within CA, it ranks 987 of 2,555.
Learn more
Before leaning on 92508's figures: the frost range explains how to read the range around Riverside's dates instead of trusting one, while local microclimates explains what one yard in Riverside can differ from the 92508 normal.